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Bernalite

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Formula:
Fe(OH)
 
3
· nH
 
2
O (n = 0.0 to 0.25)
System:OrthorhombicColour:Dark bottle-green to ...
Hardness:4
Member of:Söhngeite Group
Name:
For John Desmond Bernal (1901-1971), eminent British crystallographer and historian of science.


Söhngeite Group.
A highly unusual, pseudo-cubic, bottle-green iron hydroxide.

Classification of Bernalite

IMA status:Approved
Strunz 8th edition ID:4/F.15-30
Nickel-Strunz 10th (pending) edition ID:4.FC.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
C : Hydroxides with OH, without H2O; corner-sharing octahedra
Dana 8th edition ID:6.3.5.3

6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
3 : X(OH)3
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Type Occurrence of Bernalite

Type Locality:Broken Hill, Yancowinna Co., New South Wales, Australia
General Appearance of Type Material:Flattened pyramidal crystals and pseudo-octahedra, to 3 mm.
Place of Conservation of Type Material:Museum of Victoria, Melbourne, Australia;
South Australian Museum, Adelaide, Australia (No. G17627)
Year of Discovery:1992
Geological Setting of type material:On a museum specimen from a metamorphosed Pb-Zn deposit, probably from the surface oxidation zone
Associated Minerals at type locality:
GoethiteCoronadite

Physical Properties of Bernalite

Lustre:Adamantine, Vitreous, Resinous
Diaphaneity (Transparency):Transparent, Opaque
Colour:Dark bottle-green to yellow-green; yellowish bottle-green in thin section
Streak:Apple-green
Hardness (Mohs):4
Tenacity:Brittle
Cleavage:None Observed
Fracture:Irregular/Uneven, Conchoidal
Density (measured):3.32 g/cm3
Density (calculated):3.35 g/cm3

Crystallography of Bernalite

Crystal System:Orthorhombic
Class (H-M):mmm (2/m 2/m 2/m) - Dipyramidal
Space Group:Pmmn {P21/m 21/m 2/n}
Cell Parameters:a = 7.544Å, b = 7.56Å, c = 7.558Å
Ratio:a:b:c = 0.998 : 1 : 1
Unit Cell Volume:V 431.05 ų (Calculated from Unit Cell)
Z:8
Morphology:Flattened pyramidal crystals, pseudo-octahedral to pseudo-cubic, with slightly concave faces; also skeletal aggregates
Twinning:Polysynthetic, crosshatched, observed in thin section, probably pinacoidal.
Comment:Originally described with space group Immm.
X-Ray Powder Diffraction:
d-spacingIntensity
3.784 (100)
1.692 (17)
2.393 (16)
2.676 (15)
1.892 (10)
1.545 (9)
2.023 (6)
Comments:Recorded on type material

Optical Data of Bernalite

Type:Biaxial
RI values: n = 1.92 - 1.94
Maximum Birefringence:δ = 0.000

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Very High
Dispersion:r > v, strong

Chemical Properties of Bernalite

Formula:
Fe(OH)
 
3
· nH
 
2
O (n = 0.0 to 0.25)
Simplified for copy/paste:Fe(OH)3·nH2O (n = 0.0 to 0.25)
Essential elements:Fe, H, O
All elements listed in formula:Fe, H, O
Analytical Data:Averages of eight electron microprobe analyses of type material; Fe3+ confirmed by Mössbauer spectroscopy; H2O and CO2 determined with a CHN analyzer (IR spectrophotometry)
SiO2   (2.99)
Fe2O3 (65.53)
ZnO    (1.13)
PbO    (2.70)
H2O   (25.2)
CO2    (1.0)

sum    98.55 wt.-%
Empirical Formula:
(Fe
3+
0.93
Si
 
0.06
Zn
 
0.01
)
 
=1.00
[(OH)
 
2.95
O
 
0.04
]
 
=2.99
· [(H
 
2
O)
 
0.04
(CO
 
2
)
 
0.03
Pb
 
0.01
]
 
=0.08
Common Impurities:C,Pb,Si,Zn

Relationship of Bernalite to other Species

Member of:Söhngeite Group
Other Members of Group:

- +
Dzhalindite
In(OH)
 
3
Söhngeite
Ga(OH)
 
3
Related Minerals - Nickel-Strunz Grouping):

- +
4.FC.05Dzhalindite
In(OH)
 
3
4.FC.05Söhngeite
Ga(OH)
 
3
4.FC.10Burtite
Ca[Sn(OH)
 
6
]
4.FC.10Mushistonite
(Cu,Zn,Fe
2+
 
)[Sn(OH)
 
6
]
4.FC.10Natanite
Fe
2+
 
[Sn(OH)
 
6
]
4.FC.10Schoenfliesite
Mg[Sn(OH)
 
6
]
4.FC.10Vismirnovite
Zn[Sn(OH)
 
6
]
4.FC.10Wickmanite
Mn
2+
 
[Sn(OH)
 
6
]
4.FC.15Jeanbandyite
(Fe
2+
 
,Mn
2+
 
)[Sn
4+
 
(OH)
 
6
]
4.FC.15Mopungite
Na[Sb
5+
 
(OH)
 
6
]
4.FC.15Stottite
Fe
2+
 
[Ge
4+
 
(OH)
 
6
]
4.FC.15Tetrawickmanite
Mn
2+
 
[Sn
4+
 
(OH)
 
6
]
4.FC.20Ferronigerite-2N1S
Sn(Fe,Mg)Al
 
6
O
 
11
(OH)
4.FC.20Magnesionigerite-6N6S
Sn(Mg,Fe)
 
2
Al
 
8
O
 
15
(OH)
4.FC.20Magnesionigerite-2N1S
Sn(Mg,Fe)Al
 
6
O
 
11
(OH)
4.FC.20Ferronigerite-6N6S
Sn(Fe,Mg)
 
2
Al
 
8
O
 
15
(OH)
4.FC.20Zinconigerite-2N1S
Sn(Zn,Fe,Mg)Al
 
6
O
 
11
(OH)
4.FC.20Zinconigerite-6N6S
4.FC.25Magnesiotaaffeite-6N’3S
Mg
 
2
BeAl
 
6
O
 
12
4.FC.25Magnesiotaaffeite-2N’2S
Mg
 
3
Al
 
8
BeO
 
16

Other Names for Bernalite

Synonyms:
IMA1991-032
Other Languages:
German:Bernalit
Russian:Берналит
Spanish:Bernalita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:None

References for Bernalite

Reference List:

- +
Birch, W. D., Pring, A., Reller, A. and Schmalle, H. W. (1992): Bernalite: a new ferric hydroxide with perovskite structure. Naturwissenschaften 79, 509-511.

Birch, W. D., Pring, A., Reller, A. and Schmalle, H. W. (1993): Bernalite, Fe(OH)3, a new mineral from Broken Hill, New South Wales: Description and structure. American Mineralogist 78, 827-834.

McCammon, C. A., Pring, A., Keppler, H. and Sharp, T. (1995): A study of bernalite, Fe(OH)3, using Mössbauer spectroscopy, optical spectroscopy and transmission electron microscopy. Physical Chemistry of Minerals 22, 11-20.

Anthony, Bideaux, Bladh & Nichols (1997), Handbook of Mineralogy, Vol. III, Mineral Data Publishing: 53.

Kolitsch, U. (1998): Bernalite from the Clara mine, Germany, and the incorporation of tungsten in minerals containing ferric iron. Canadian Mineralogist 36, 1211-1216.

Welch, M. D.; Crichton, W. A.; Ross, N. L. (2005): Compression of the perovskite-related mineral bernalite Fe(OH)3 to 9 GPa and a reappraisal of its structure. Mineralogical Magazine, 69, 309-315.

Internet Links for Bernalite

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  • Raman and XRD data at RRUFF project
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  • Bernalite details from Handbook of Mineralogy (PDF)
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  • Localities for Bernalite

    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Australia
     
    • New South Wales
      • Yancowinna Co.
    Naturwiss.(1992) 79, 509-511
    R&M. 71:160-161 (1996); Australian Min. 3:1 (1997)
    Germany
     
    • Baden-Württemberg
      • Black Forest
        • St Blasien
          • Urberg
    Lapis 33 (10), 62-63
        • Wolfach
          • Oberwolfach
            • Rankach valley
    Walenta, K. (1992): Die Mineralien des Schwarzwaldes. Chr. Weise Verlag, München, 336 pp. (in German); Walenta, K. (1995): Neue Mineralfunde von der Grube Clara. 6. Folge, 1. Teil. Lapis 20 (5), 33-38 (in German); Kolitsch, U. (1997): Uranosphärit und weitere neue Mineralfunde von der Grube Clara im Schwarzwald. Mineralien-Welt 8 (3), 18-26 (in German) ; Kolitsch, U. (1998): Bernalite from the Clara mine, Germany, and the incorporation of tungsten in minerals containing ferric iron. Can. Mineral. 36, 1211-1216; KOLITSCH, U. (1997): Uranosphärit und weitere neue Mineralfunde von der Grube Clara im Schwarzwald. - Mineralien-Welt 8 (3), 18-26.
    • Saxony
      • Vogtland
        • Oelsnitz
          • Schönbrunn
    Thalheim, K. & Kaden, M. (2006): Die Sammlung Sachsen - Interessante Neubestimmungen. Pp. 154-155 in: Lange, J. M. & Kühne, E., Eds. (2006): Das Museum für Mineralogie und Geologie in den Staatlichen Naturhistorischen Sammlungen Dresden. Von der kurfürstlichen Kunstkammer zum staatlichen Forschungsmuseum. Museum für Mineralogie und Geologie, Staatliche Naturhistorische Sammlungen Dresden, Dresden, Germany, 200 pp.
    Italy
     
    • Liguria
      • Genova Province
        • Sestri Levante
    Dott. Cristina Carbone-Dipteris-Genova: analysis June 2007 (paper in preparation)
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